The Messenger of Allah ﷺ fell down from a horse and his right side was grazed, and the rest of the hadith is the same with the addition of these words:" When he (the Imam) says prayer standing, you should also do so."
أَنَّ رَسُولَ اللَّهِ ﷺ صُرِعَ عَنْ فَرَسٍ فَجُحِشَ شِقُّهُ الأَيْمَنُ بِنَحْوِ حَدِيثِهِمَا وَزَادَ فَإِذَا صَلَّى قَائِمًا فَصَلُّوا قِيَامًا
The Messenger of Allah ﷺ rode a horse and fell down from it and his right side was grazed, and the rest of the hadith is the same, and (these words) are found in it:" When he (the Imam) says prayer in an erect posture, you should also say it in an erect posture."
أَنَّ رَسُولَ اللَّهِ ﷺ رَكِبَ فَرَسًا فَصُرِعَ عَنْهُ فَجُحِشَ شِقُّهُ الأَيْمَنُ بِنَحْوِ حَدِيثِهِمْ وَفِيهِ إِذَا صَلَّى قَائِمًا فَصَلُّوا قِيَامًا